Early Myford quick change gearbox.

[sparky mikeParticipant @sparkymike]

Hi,

I am progressing slowly with the early type quick change gearbox for my Super 7 lathe. This is the one where the lead screw does not pass through the box.

I will at some time be needing the threat cutting chart for the early box which I understand is not the same as the later box. Can anyone scan me a copy of the relevant page from the early super 7 / gearbox manual please.

I am still looking for the external gears for the left hand side of the box, ie. the two cluster gears and the very large wide gear. If anyone out there has spare ones, please PM me. Thanks.

Mike.

Edited By sparky mike on 03/03/2013 09:52:12

[sparky mikeParticipant @sparkymike]

[john fletcher 1Participant @johnfletcher1]

I once had a similar super 7, and a couple of gears needed relacing. I got replacement gears from HPC gears in Chestfield, this was their phone number 01246 268080 at that time. I think one of the gears needed bushing or boring not sure. Ted

[Brian WoodParticipant @brianwood45127]

HPC Gears are still at Chesterfield, they also have a website.

http://www.hpc-gears.co.uk

contact sales@hpc-gears.co.uk

They will want to know what pressure angle to make the gears to and the DP size.

I don't know the box well enough to help sparky mike, can others advise?

Brian

[John Stevenson 1Participant @johnstevenson1]

Stock gears from HPC are all 20 degrees. Myfords are 14.5 and don't even think about asking HPC to make these, cheaper to buy a new S7

However as these three gears only run together and don't mate to any others there is no reason why you can't use a full set of three 20 degree PA gears.

[sparky mikeParticipant @sparkymike]

Hi John,

On my gearbox, being the early type ,what takes the drive from the reverse tumbler gears on the headstock to the gearbox external gears? I would assume that there is a gear located on a keyway which locks on to one of the 19/57 T gears.? Or does it just mate with the first gear on the quick change gearbox quadrant. If anyone could post a photo showing the correct set-up it would be a great help. (or PM me for my email address.) I have obtained the with the 12 T / 30T slow feed gear so things are progressing.

[Eddy SpriggsParticipant @eddyspriggs]

Hello Sparky,

If it helps, I have a Myford for sale on Ebay which has a photo showing the gears you are talking about. (If I've read your letter correctly).

Eddy.

[sparky mikeParticipant @sparkymike]

Hi Eddy,

I think I found your grey Myford lathe on Ebay. (very nice too.) The photo of the gears is nice and sharp and is a great help. I was thinking I needed a third intermediate gear, but now it looks like I can buy a few beers instead !!

Many thanks for all replies so far.

Mike.

 

Edited By sparky mike on 03/03/2013 16:46:26

[DMRParticipant @dmr]

Mike,

There is no need to complicate your life thinking you need different thread-cutting abilities with the early gearbox. There is a times (x2) involved, and that is all the info you basically need. The cogs at the left side between tumbler and gearbox input are identical to the later model. We have conversed on this last summer and looking back I see that I failed to reply to one of your mailings as you dropped off the bottom of the visible list. Sorry.

I have sent you a PM with my e-mail address and can supply all the tables/diagrams and any other info you need.

Dennis

[sparky mikeParticipant @sparkymike]

Well after a year of trials and tribulations, I have finally got the gearbox fitted to the lathe and better still, it works. Many thanks for all the help on this matter especially Dennis, who provided me with a great deal of help and some parts as well.

Now I would like to get proficient in the art of screw-cutting, but there is not much information on how to use the gearbox in the Myford gearbox manual.

Am I correct in the following. Select thread pitch to be cut on gearbox and then engage drive. Retract tool at end of pass and stop motor. Reverse motor and go back to start of thread. Revert to forward drive on motor and increase depth of cut, etc etc. I am assuming that if I reverse the gearbox on the tumbler gears I could perhaps be out of sync. with the thread cutting, or am I incorrect in that respect?

Mike.

[davebParticipant @daveb17630]

If you do it that way, your lathe will be worn out in no time, use that method for metric and other strange threads.

For Imperial threads use the Thread Dial Indicator (Myford Part). Do not stop motor, disengage clasp nut lever, retract topslide, wind saddle back with handwheel, advance topslide, re-engage clasp nuts when correct division shows on TDI, repeat until thread is cut to depth. All Imperial threads will pick up if you always engage the clasp nuts at the same number but you can save time with some threads because they will pick up at other divisions of the DTI dial. Basic method is the same with gearbox or changewheels. There are a lot of refinements to all this but for cutting the occasional threads, the above method serves.

Dave

[sparky mikeParticipant @sparkymike]

Hi Dave, thanks for your reply, I had thought that the dial indicator would not be needed when the gearbox was used, hence the interest in Gray's reversing attatchment ? However, if that device is engaged constantly, would that cause the same amount of wear that you mention with my trial efforts?

Mike.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by daveb on 25/09/2013 00:34:33:

If you do it that way, your lathe will be worn out in no time, use that method for metric and other strange threads.

Er.. What's special about Myfords that they wear out so quickly if reversed?

Russell.

[davebParticipant @daveb17630]

If you do not disengage the clasp nuts and reverse the drive, the thread will always pick up. This applies to both changewheels and gearboxes, it is really the only practical way to do it if you are cutting metric threads on an Imperial machine or vice versa. My only objection to doing it this way (for Imperial threads) is that it's slow and tedious but I suppose it depends on how much threading you have to do. If you disengage the clasp nuts, you will need the TDI to re-engage at the correct position, with or without gearbox. I have only had a quick look at Gray's device, looks good but again, depends on how much threading you need to do. Wear, starting and stopping the motor twice for each cut probably wouldn't do it a lot of good (applies to a single phase motor) but if you have an inverter system, this wouldn't be important. By not disengaging the clasp nuts, the leadscrew and nuts get exactly twice as much wear.

A little tip, check that the sliding selector lever lines up well with the label on top of the gearbox. Mine doesn't, I once cut a beautiful 11 TPI thread, trouble was I needed 10 TPI. Yes, I know, I should have checked.

Dave

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